Epinephrine (i.e., adrenaline) is a catecholamine with the following chemical structure:

Epinephrine stimulates the alpha- and beta-adrenergic receptors of the sympathetic nervous system. Epinephrine binds to these adrenergic receptors leading to relief of many life-threatening symptoms of anaphylaxis including: relaxation of the smooth muscle in the bronchi of the lungs opening up the constricted airways; constriction of the blood vessels leading to decreased swelling of the tongue and throat and increased blood pressure; and finally, increased heart rate preventing or reversing cardiovascular collapse.
Epinephrine is commercially available as an injection (Adrenalin® a trademark of and available from Par Sterile Products, LLC) and an auto-injector (EpiPen® a trademark of and available from Mylan, Inc. and AuviQ® a trademark of and available from Sanofi Corporation). Epinephrine was previously available as a nasal spray (Adrenalin®) and an aerosol spray (Primatene® Mist trademark of Armstrong Pharmaceuticals, Inc.). Racepinephrine is commercially available as a 2.25% oral inhalation solution for use in nebulizers (S2® is available from Nephron Pharmaceuticals, Inc.). Epinephrine differs from racepinephrine in that epinephrine consists of only the L-isomer and racepinephrine is a 50/50 mixture of both the L- and D-isomers.
U.S. Pat. No. 8,628,805 is directed to a stable liquid adrenaline/bisulfite composition wherein the molar ratio of adrenaline to bisulfite is 1.31-2.20:1. U.S. Patent Application Publication No. 2012/0322884 A1 is directed to epinephrine nanoparticles, which can be incorporated into sublingual tablets. U.S. Patent Application Publication No. 2007/0202163 A1 is directed to epinephrine tablets for sublingual administration, which contain between 12% and 48% epinephrine. World Intellectual Property Organization (“W.I.P.O.”) Publication No. 2014/127018 A1 is directed to a stable aqueous epinephrine formulation that requires cyclodextrin. W.I.P.O. Publication No. 2014/057365 A1 is directed to an injectable epinephrine formulation.
While there are various epinephrine formulations currently available, there remains a need in the art for a quick-onset spray formulation.